1. Field of the Invention
The present invention relates to a prepreg, a laminate, a printed wiring board, and a semiconductor device that uses these elements. The laminate of the present invention includes a laminate in which one surface or both surfaces are coated with a metal foil, namely a metal-clad laminate.
2. Description of the Prior Art
In recent years, the amounts of prepregs used for electrical insulation, laminates and printed wiring boards have increased as semiconductor devices have been reduced in size and weight and improved in terms of functionality. Conventionally, the terminals on semiconductor elements and the circuits on printed wiring boards have been connected with Au wire, Au bumps or solder balls, but recently the use of Cu wire has been increasing, with the aim of reducing cost.
However, there have been reports that when Cu wire is used in a bias test under conditions of high temperature and high humidity (HAST), occurrences of open failure may occur at the junctions between the Cu wire and Al pads on the semiconductor element.